Field
An embodiment of the present invention relates to a semiconductor memory device.
Description of the Related Art
In the field of semiconductor memory devices, a three-dimensional type NAND type flash memory has been gathering attention as a device capable of achieving a high degree of integration, without being confined to a limit of resolution of lithography technology. This three-dimensional type NAND type flash memory comprises a stacked body in which a plurality of conductive layers functioning as a word line or select gate line and inter-layer insulating layers are stacked alternately above a semiconductor substrate, and comprises a columnar semiconductor layer disposed so as to penetrate this stacked body. This semiconductor layer functions as a channel of a memory cell. In addition, the three-dimensional type NAND flash memory comprises a block layer, a charge accumulation layer, and a tunnel insulating layer disposed sequentially between the conductive layer and the semiconductor layer in the stacked body.
Even in the three-dimensional type NAND type flash memory having the above-described structure, read disturbance in a fringe electric field or charge leakage from the charge accumulation layer due to effects of miniaturization, are a problem, similarly to in other semiconductor devices.